TOOL HOLDER CLAMP ASSEMBLY FOR CUTTING INSERTS AND
ITS PRESSING PLATE
Technical Field
[0001] This disclosure is related to a tool holder clamp assembyy for cutting
inserts using a pressing plate.
Background Art
[0002] In tool holders for machining a work-piece, especially for turning
applicaiion,, the clamping force upon inserts is often insufficient so that small
movemenss of the inserts in the pocket during machining causes the tool life to
decrease and someiimes leads to the breakage of inserts, In addition, chips
generated during machining are impinged onto the clamp with high pressure so
that the clamp is severely worn out; therefore the tool life decreases rapidly. To
solve this problem, clamps engaged with pressing plates formed of a hard
material are proposed for use in tool holders.
[0003] Howeve,, since conventional clamp plates are fastened to the clamps by
separate screws and conneciing plates, handiing is inconvenient and the number
of parts is increased. Also, since additional thread tab machining is needed,
there is an extra machining cost and breakage may occur due to the weakened
portion by the tab. In addition, there is a structural weakness against the
rotational movement of the clamp plate.
Disclosure
Technical Problem
[0004] The present disclosure aims to provide a clamp assembly and a tool
holder which creates an excellent damping force by using a pressing plate
having a simple structure, and which also allows easy coupiing of the pressing
plate.

Technical Solution
[0005] A pressing plate for a clamp configured to fasten a cutting insert to a tool
holder pocket according to the present disclosure comprises upper and lower
surfaces, a front nose portion, and a rear end portion, and is provided with a
keyhole shaped groove having an enlarged inner cavity open toward the rear end
by a narrow neck extending thicknesswise.
[0006] A clamp assembly for fastening a cutting insert to a tool holder according
to the present disclosure comprises: a clamp comprising a body portion provided
with a screw hole for a clamping screw to pass through, a forward protrusion
formed at the front portion of the body and extending downward, a rear
protrusion formed at the rear end portion of the body and extending downward,
and a bridge connecting the forward protrusion and the central portion of the
body, and the pressing plate described above. The forward protrusion is inserted
into the enlarged inner cavity and the bridge is inserted into the narrow neck of
the keyhole groove so that the pressing plate is coupled to the clamp.
[0007] The clamp assembly according to the present disclosure may have a
pressing plate whose front nose portion has a curved surface slanted
downwardly from the upper surface to the lower surface and whose rear end
portion comprises a vertical flat surface.
[0008] The pressing plate according to the present disclosure may have a
reinforcing protrusion formed on the upper surface around the enlarged inner
cavity.
[0009] The pressing plate according to the present disclosure may have a pin
receiving depression formed near the rear end on the lower surface across the
narrow neck.
[0010] The clamp assembly according to the present disclosure may further
comprise a fixing pin, and a pin hole formed across the bridge of the clamp,
wherein the fixing pin is inserted into the pin hole and received in the pin

receiving depression.
Advantageous Effects
[0011J The clamp assembly using the pressing plate according to the present
disclosure allows easy handling and a smaller number of parts. Also, the
forward protrusion is structurally reinforced by a bridge and the life time of the
damp is greatly extended. Also, rotation of the pressing plate in the clamp is
prevented. The structural strength of the pressing plate is reinforced and the
clamping force is increased by transferring the pressing force more uniformly to
the upper surface of the insert. The present disclosure allows various types of
inserts to be mounted in the same tool holder regardless of insert-hole shapes,
by changing the clamp and the pressing plate.
Description of Drawings
[0012J Fig.1 is a sectional view depicting a tool holder assembly in accordance
with the present disclosure.
[0013] Fig.2 is a planar view of the tool holder assembly of Fig. 1.
[0014] Fig.3 is a perspective view depicting a clamp in accordance with the
present disclosure.
[0015] Fig.4 is a perspective view depicting a damp assembly in accordance
with the present disclosure.
[0016] Figs. 5 and 6 are perspective views depicting a pressing plate in
accordance with the present disclosure.
[0017] Fig. 7 is a planar view of the pressing plate shown in Figs. 5 and 6.
[0018] Figs. 8 and 9 are sectional views depicting alternative embodiments of
■> tool holder assemblies in accordance with the present disclosure.

Mode for Invention
[0019] Hereinafter, pressing plates, clamp assemblies engaged with the
pressing plates, and tool holders with inserts clamped by the clamp assemblies
according to embodiments of the present disclosure are described. The figures
attached to the present disclosure are merely for convenience of explanation,
and the shapes and the relative scales may be exaggerated or abridged.
[0020] Fig.1 is a sectional view depicting a tool holder assembly in accordance
with the present disclosure and Fig.2 is a planar view of the tool holder assembly
of Fig. 1. In the tool holder assembly of Fig. 1, a cutting insert 300 with a central
hole 301 is clamped to a tool holder 500 using a clamp 200. Generally, the
cutting insert 300 is mounted on a shim plate 400 which is fastened to the tool
holder 500 by a screw 410.
[0021] Fig.3 is a perspective view depicting a clamp in accordance with the
present disclosure. The clamp 200 comprises a body provided with a screw
hole 201 for a clamping screw 260 to pass through, a forward protrusion 210
formed at the front portion of the body, extending downward and received in the
central hole 301 of the insert 300, a rear protrusion 230 formed at the rear portion
of the body, extending downward and having a rear contact surface configured to
come in contact with a rearward slanting surface 510 of the tool holder 500, and
a bridge 240 connecting the forward protrusion 210 and the central portion 220 of
the body. The bridge 240 reinforces the structural strength of the forward
protrusion 210, which is structurally weak, and prevents breakage dUring
machining. As shown in Fig. 3, the bridge 240 may have a cutout 242 formed on
the border to the forward protrusion 210 to alleviate the stress concentration
bUildup at the border portion.
[0022] Fig.4 is a perspective view depicting a clamp assembly in accordance
with the present disclosure. The clamp assembly is assembled by coupling a
pressing plate 100 to a clamp 200.

[0023] Figs. 5 and 6 are perspective views depicting a pressing plate in
accordance with the present disclosure at different angles, and Fig. 7 is a
corresponding planar view. The pressing plate 100 is used for a clamp 200
fastening a cutting insert to a tool holder pocket. The pressing plate 100
comprises upper and lower surfaces 110.120. a front nose portion 130, and a
rear end portion 140, and is provided with a keyhole shaped groove 150 having
an enlarged inner caVity 151 open toward the rear end by a narrow neck 152
extending thicknesswise. The pressing plate is made of a super hard material to
resist wear and endure for a long time. The pressing plate also allows the
pressing force of the clamp to transfer strongly to a large area of the upper
surface of the insert.
{0024] The forward protrusion 210 of the damp is inserted into the enlarged
inner cavity 151 of the pressing plate and the bridge 240 of the clamp is inserted
into the narrow neck 152 of the keyhole groove 150 so that the pressing plate
100 is coupled to the clamp 200 to form a clamp assembly.
[0025] In the pressing plate, the front nose portion 130 may have a curved
surface 131 slanted downwardly from the upper surface 110 to the lower surface
120 for smooth chip evacuation and the rear end portion 140 may comprise a
vertical flat surface 145. The pressing plate may have a reinforcing protrusion
115 formed on the upper surface 110 around the enlarged inner caVity 151.
This reinforces the structural strength of the pressing plate and also transfers the
pressing force more uniformly to the upper surface of the insert. The pressing
plate may have a pin receiving depression 125 which is formed near the rear end
140 on the lower surface 120 across the narrow neck 152.
[0026] The underside of the clamp may be provided with a vertical support
surface 225 which corresponds to the vertical flat surface 145 of the pressing
plate 100. Therefore, if contact is made between the vertical flat surface 145 and
the vertical support surface 225, the contact prevents rotation of the pressing
plate in the clamp and reduces the rotational force applied on the bridge. The
reinforcing protrusion 115 of the pressing plate 100 comes in contact with the

underside of the front portion of the damp body around the forward protrusion
210.
[0027] The clamp 200 may be provided with a pin hole 241 formed across the
bridge 240. The clamp assembly may further comprise a fixing pin 245, and the
fiXing pin 245 is inserted into the pin hole 241 and received in the pin receiving
depression 125 so that the clamp assembly is integrally engaged with a pressing
plate Generally the fixing pin is spring steel having a straight shape and allows
elastic coupiing to the pin hole 241.
{00281 The dlamp assembly using the pressing plate according to the present
disclosure allows simple fixing by means of one fixing pin without using any other
fastening means such as screws so that handiing is easier and the number of
parts is reduced. Also, since the forward protrusion, which is structurally weak,
is structurally reinforced by a bridge, the life time of the clamp is greatly extended.
The vertical flat surface of the pressing plate has the effect of preveniing rotation
of the pressing plate in the clamp and reducing the rotational force applied on the
bridge. The reinforcing protrusion of the pressing plate reinforces the structural
strength of the pressing plate and also increases the clamping force by
transferring the pressing force more uniformly onto the upper surface of the
insert.
[0029} The present disclosure allows various types of inserts to be mounted in
the same tool holder, regardless of their shapes, by changing only the clamp and
the pressing plate. For example, although the tool holder of Fig. 1 is described for
a cutting insert with a vertically pierced damping hole, the concept of the present
disclosure may be applied to tool holders conftgured to damp inserts with a
central dimple or flat inserts without holes 300a, 300b as shown in Figs. 8 and 9,
respeciively. In these embodiments, the same pressing plate 100 may be used
for securing various types of inserts 300a, 300b to the tool holder haVing the
same pocket shape with only a slight difference in the length and shape of the
forward protrusion of the clamp 200a, 200b.

[0030] The tool holder assemblies using the clamp assemblies disclosed above
may have various other embodiments without departing from the basic concept
of the present disclosure. Accordingly, all the disclosed embodiments must be
understood as being exemplary only and must not be construed to be the limit of
the present disclosure. Accordingly, the range of protection for the present
disclosure must be determined not by an embodiment described hereinabove,
but by the attached claims. An alternative that is equivalent to the attached
claims is included in the range of protection of the attached c\atms.

CLAIMS
1. A pressing plate for a clamp configured to fasten a cutting insert to a tool
holder pocket, wherein the pressing plate comprises upper and lower surfaces, a
front nose portion, and a rear end portion, and is provided with a keyhole shaped
groove having an enlarged inner cavity open toward the rear end by a narrow
neck extending thicknesswise.
2. The pressing plate according to claim 1, wherein the front nose portion has a
curved surface slanted downwardly from the upper surface to the lower surface
and the rear end portion comprises a vertical flat surface.
3. The pressing plate according to claim 1, wherein a reinforcing protrusion is
formed on the upper surface around the enlarged inner cavity.
4. The pressing plate according to claim 1, wherein a pin receiving depression
is formed near the rear end on the lower surface across the narrow neck.
5. A clamp assembly for fastening a cutting insert to a tool holder, wherein the
clamp assembly comprises:
a clamp comprising a body portion provided with a screw hole for a
clamping screw to pass through, a forward protrusion formed at the front portion
of the body and extending downward, a rear protrusion formed at the rear end
portion of the body and extending downward, and a bridge connecting the
forward protrusion and the central portion of the body; and
a pressing plate comprising upper and lower sUrfaces, a front nose
portion, and a rear end portion, and being provided with a keyhole shaped
groove having an enlarged inner cavity open toward the rear end by a narrow
neck extending thicknesswise, wherein the forward protrusion is inserted into the
enlarged inner cavity and the bridge is inserted into the narrow neck of the
keyhole groove so that the pressing plate is coupled to the clamp.
6. The clamp assembly according to claim 5, wherein the rear end portion of

the pressing plate comprises a vertical flat surface and the underside of the
clamp is provided with a vertical support surface which corresponss to the
vertical flat surface of the pressing plate.
7. The clamp assembyy according to claim 5, wherein a reinforcing protrusion is
formed on the upper surface of the pressing plate around the enlarged inner
cavity, and the reinforcing protrusion comes in contact with the underside of the
front portion of the clamp body.
8. The clamp assembly according to claim 5, wherein the bridge of the clamp
has a cutout formed on the border portion with the forward protrusio..
9. The clamp assembly according to claim 5, wherein the clamp assembly
further comprises a fixing pin, and a pin receiving depression is formed across
the narrow neck near the rear end on the lower surface of the pressing plate, a
pin hole is formed across the bridge of the clamp, and the fixing pin is inserted
into the pin hole and received in the pin receiving depression.
10. A tool holder assembly using the clamp assembly according to any one of
claims 5 through 9.

ABSTRACT

A clamp assembly for fastening a cutting insert to a tool holder is
disclosed herein. The clamp assembly comprises: a body portion provided with a
screw hole, a forward protrusion formed at the front portion of the body and
extending downward, a rear protrusion formed at the rear end portion of the body
and extending downward, and a bridge connecting the forward protrusion and the
central portion of the body; and a pressing plate comprising upper and lower
surfaces, a front nose portion, a rear end portion, and is provided with a keyhole
shaped groove having an enlarged inner cavity open toward the rear end by a
narrow neck extending thicknesswise. The forward protrusion is inserted into the
enlarged inner cavity and the bridge is inserted into the narrow neck of the
keyhole groove so that the pressing plate is coupled to the clamp.